Portable communication devices, such as cellular telephones, personal digital assistants (PDAs), WiFi transceivers, and other communication devices transmit and receive communication signals at various frequencies that correspond to different communication bands and at varying power levels. Each of these devices uses a power amplifier to amplify the information signal for over-the-air transmission and some manner of power control to monitor and regulate the power output of the power amplifier. One such power amplifier and power control topology uses separate dies, also referred to as integrated circuit (IC) chips, for the power amplifier and for the power control circuitry. Locating the power amplifier and power control circuitry on separate dice provides a high degree of radio frequency (RF) isolation between the power amplifier and the power control circuitry. Additional isolation is provided by electrical bond wires that are used to electrically couple the power amplifier to the power control circuitry. A high degree of isolation between the power amplifier and the power control circuitry promotes a stable power control loop.
While multi-chip power amplification topologies have worked adequately, there is a move in the industry toward single-chip power amplifier topologies, which combine power amplification circuitry and power control circuitry on a single die. Unfortunately, combining a power amplifier and power control circuitry on a single die degrades the isolation between the power amplifier and power control circuitry and also makes accurate closed loop power control more problematic.
Therefore, there is a need for a single-die power amplification topology that overcomes the above-mentioned challenges.